1. Field of the Invention
The invention concerns a method of patching the lining of a large glass-lined reactor. The novel method can also be used to patch glass in other uses.
2. Description of the widely Related Art
Production-size glass-lined reactors are widely used in the chemical, food processing, and pharmaceutical industries. Among uses in the chemical industry are nitration, halogenation, sulfuration, oxidation, polymerization, and esterification. The reactors are constructed by fusing a glass lining to a steel jacket.
The glass lining can be damaged in a variety of ways such as by thermal stresses or by accidentally rough contact during cleaning. Because a production-size reactor is expensive and because production can be halted for prolonged periods of time if it needs to be replaced, efforts are made to repair any damage on site. It is estimated that on the average, the glass lining of a reactor is repaired 2-3 times per year and that the glass linings of production-size reactors are repaired as many as 20,000 times every year in the United States alone.
Small cracks and pinholes are patched with special resins and cements, typically using repair kits supplied by the reactor manufacturer. The two most widely used kits are called "Furan" and "Silicate" by Pfaudler Division of Standard Oil of Ohio. Similar kits are supplied by De Dietrich of Union N.J.; Ceramic Coating Co. of Newport, N.Y.; A&A Industries; Artisan Industries; Fluidyne Corp.; Tekmar Co.; and Titanium Industries. When a crack or hole extends through the lining to the steel jacket, a repair plug of tantalum or hastalloy can be screwed into the steel jacket to hold a patch in place together with a gasket of porous polytetrafluoroethylene.
All such repairs have short useful lives and sometimes fail almost immediately. Furthermore, the resin or cement kits emit volatiles that could involve danger of explosion. It usually is necessary to take the reactor out of service for from 24 to 48 hours to make a repair with such a kit, although this often is done when the reactor needs cleaning that would require the same amount of down time without any repair.
Another repair technique is to fuse glass over the damaged area, but this requires great skill and can be exceedingly difficult to perform because of poor accessibility to the area needing repair. It also is much more expensive than to use a resin or cement kit or a plug.